LCD display with PIC Microcontrollers

Intelligent instrumentation design, usually have to be displayed on the monitoring and control information. By the instrument power, volume and other conditions, CRT monitors tend to be less generally applicable. The semiconductor LED, although able to show digital and a few letters, but not flexible display a variety of text, graphics, tables, etc., has a big limitation. The LCD monitor has a function as a strong, low power consumption, show a clear, light construction, etc., are widely used in various types of intelligent instrument display. MICROCHIP PIC microcontroller is the United States launched a high-performance single-chip, compared to traditional MCS51 series microcontrollers, it has a built-in function modules and more interference, good speed, low power consumption, is widely used in industrial control applications.

SED1520 structure, command and its interface circuit with PIC microcontroller

SED1520 mainly by the timer counter, the ranks of the address register and decoder circuits, display RAM, MPU interface circuit, LCD interface circuit. It interfaces with external three main parts: one is the power, reset and clock signal; part of the LCD interface, the other is with the MPU (microprocessor) interface. LCD interfacing with the LCD module is generally provided by the manufacturer responsible for the LCD module, users only need to grasp the part with the MPU interface. In addition, SED1520 also need to provide the clock signal 2KHZ
It shows a total of 4 memory (page address corresponding to 0 to 3), each page has 80 bytes (corresponding to the column address is 0 ~ 79), each byte in the 8-bit data corresponds to display 8:00 on the same column line. This column address pointer is 80 bytes management unit. Electronic Components Column address pointer is a 7 plus 1 counter. By it and the page address register to specify the display memory of the only one unit. SED1520 in the RAM 32 lines, divided into 4 pages of 8 lines, so if you press 8 * 8 dot matrix display characters, each page can write a single line 10 characters, write a total of 4 lines, and characters are generally 16 * 16 matrix, each row displays five characters, two lines of display. If multiple SED1520 put together, can form different size LCD display modules,
    A0: command / data selection. That data transmission is high, low-level transmission of the instruction.
 chip select signal, active low, not high then the MPU access SED1520.
      Read permission, low-level MPU read data from the SED1520 or instructions, high invalid.
 Write Enable, low-level MPU writes data to the SED1520 or instructions, high invalid.
 CL: Clock input. Provided by the PIC16F874's RC1, let it work on the PWM2 output.
 D0 ~ D7: data input and output pins.
 reset signal input, active low.
 VDD: logic power supply is.
 VSS: logic supply ground.

Article source:  http://www.icdealer.com/product-news/microchip-articles/lcd-display-with-pic-microcontrollers